SLDS Class to Filling Available Height

You can leverage Vertical Stretch. By default, grid items extend vertically unless .slds-wrap is applied to your parent grid container or you have multiple rows. If you have need multiple rows that stretch the height of the parent grid container, you can apply the class .slds-grid--vertical-stretch. Note, to vertically align elements on a cross-axis of a .slds-grid, the elements need available vertical white space. This is usually achieved by having a height applied to the .slds-grid.

<div class="slds-grid slds-grid--vertical-stretch">
  <div>Content determines the width unless otherwise set</div>
  <div>1</div>
  <div>2</div>
  <div>3</div>
</div>